Mesenchymal stem cells (MSCs) have been used experimentally for treating inflammatory disorders, partly owing to their immunosuppressive properties. The goal of the study was to determine whether TLR
ligands can enhance the therapeutic efficacy of bone marrow-derived MSCs for the treatment of
inflammatory bowel disease. Mice (C57BL6) were administered with 4%
dextran sulfate sodium (DSS) in
drinking water for 7 days and injected with MSCs on days 1 and 3 following DSS ingestion. Our results demonstrated that among various TLR
ligands, MSCs treated with
polyinosinic-polycytidylic acid [
poly(I:C)], which is a TLR3
ligand, more profoundly induced IDO, which is a therapeutically relevant immunosuppressive factor, without any observable phenotype change in vitro. The
poly(I:C)-treated MSCs attenuated the pathologic severity of DSS-induced murine
colitis when injected i.p. but not i.v. In summary, preconditioning MSCs with
poly(I:C) might improve their efficacy in treating DSS-induced
colitis, and this effect at least partly depends on the enhancement of their immunosuppressive activity through increasing their production of IDO.